Strain relief for electrical connectors



April 1, 1952 s. L. PEDERSEN STRAIN RELIEF FOR ELECTRICAL CONNECTORS Filed April 8, 1

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f I r I I I ATTORNEY April 1, [1952 s. PEDERSEN STRAIN RELIEF FOR ELECTRICAL CONNECTORS Filed April 8, 1948 2 sHEETs 'sHEET 2 I, a I

INVENTOR JV: 11:] 1. 2:11; c f icrjcu ATTORNEY Patented Apr. 1, 1952 STRAIN RELIEF FOR ELECTRICAL CONNECTORS SvendLacss-te Pcdersen, Copenhagen, Denmark Application April 8, 1948, Serial No. 19,782

8 Claims.

This invention relates to electrical connections.

Inmy copending application Serial No. 12,658, filed March 2, 1948, I have disclosed forms of electrical connections for use in plugs and lamp sockets, as well as a wide variety of other types of appliances, by means of which the wire-ends of an electric cord may be easily and safely secured. It is an object of the present invention to provide an even more efficiently-operated and eifective arrangement.

Pursuant to the invention there is provided an arrangement into which a cord with free wireends may be inserted by a single motion, and the cord clamped and the wires connected by a single additional motion. Pursuant to the invention in certain of its aspects, moreover; there are provided cord-clamping means of such character that outward pull on the cord will tend to increase the clamping action. In various of its specific aspects the invention contemplates the provision of an electrical connection comprising two pivotally-mounted parts having cord-clamping; surfaces laterally of thepivot point and wireclamping and contact-forming surfaces at a point spaced from the pivot point, havin a cordclamping surface eccentric of the pivot-point, and having efiective and efiicient means to lock the assembly in closed position. In its still more specific aspects it contemplates the provision of means which are simple and inexpensive to manufacture and which may be assembled and disassembled without the use of screws of other difficultly-operable means.

The invention accordingly comprises an article of manufacture possessing the features, properties, and the relation of elements which will be exemplified in the article hereinafter described and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the'accompanying drawings, in which:

Figure 1 is a perspective view of an electric plug; embodying the invention, showing the same in open position;

Fig. 2 is a transverse sectional view along the line 2--2 of Fig. 1, showing the plug in closed position with a cord end clamped therein;

Fig. 3 is a transverse sectional view along the lines 33 of Fig. 2;

Fig. 4 is a perspective view of a modified form of arrangement adapted for use with a bulb socket; showing the parts in open position;

(Cl. li -3'22) Fig; 5 is a vertical sectional view of the arrangement of Fig. 4 in closed position and assembled with a socket casing; and

Fig. 6 is a transverse sectional view along the line 6-6 of Fig; 4.

In the form of construction exemplified in Figs. 1-3 there are provided a pair of insulating members It and II formed, in the present instance, entirely of insulating material and pivotally connected at I 2. The member I I is formed with a main passageway I4 which. is divided by a separator I5, which is V-shaped in the present instance, to provide channels [6 and Il which lead inwardly and laterally thru recesses 20 and 2|. At the inner sides of the recesses there are provided. resilient contact strips 22 and 23 which in the. present instance. incline outwardly toward the base of. the recesses so as to permit inward resilient movement at this point. The strips 22 and 23 are mounted on stems. 24 and 25 which serve as leads connecting the contact strips to the insertable contact arms. 26 and 21 of theplug. Notches 28 and 29 are provided in the; respective strips 22 and 23 to accommodate the wire ends.

An electric cord 30 with separated. insulated conductors 32 and 33 at its end may be readily received by the plug just described. The conductcrs, with, the insulation removed at their wire-ends 34 and 35, may be thrust along the passageway HI toward the separator I5- which will divide. them so that the end 34- will move along the channel. 16 into the recess 20 and the end 35 will move along the channel I1 into the recess 2|. The member ID is roughened as at 36 at one side of the passageway. 14 and the member II is formed with a roughened curved surface 37 at the other side of the passageway 14, this roughened surface 31 being eccentric to the pivot pin l2 so that when the members Ill and II are moved apart they will form an opening between the surfaces 36 and 31, and when they are moved together a cord 30 will be gripped firmly therebetween. As will be seen, moreover, any pull on the cord. 30 tending to withdraw it from the passageway" M will, when the assembly i0ll is closed, serve. merely to tend to pull. the surface 31 tighter against the surface 36 thus efiectively preventing any pull from loosening the connection until the members l0 and II are intentionally swung open on the pivot l2. The member H carrieslugs 38 and 39 adapted to move within the recesses 20 and 2| as the assembly'is closed; the inner surfaceof the lugs being so positioned as to, pressthe wire-endsrespectivelyagainst the resilientstrips 22' and/23. The

forward surfaces of the lugs are recessed as at 40 and 4| to accommodate excess lengths of wire.

As will be appreciated, the face 42 of the member II from which the contact arms 26 and 21 project and the alined face 43 of the member Hl provide a seat which is set against the face of a wall socket when the plug is in use. Pursuant to the invention in certain of its more specific aspects the exemplified plug provides a releasable locking means which is accessible only when access can readily be had to this seat. Thus the locking means may not be released except when the plug is removed from the socket. In the present instance this locking means consists of a toothed resilient arm 45 set in the end of the member ll adapted to snap over a toothed surface 41 in an arm-receiving slot 48.- The slot 48 is somewhat longer than the arm 45 to permit a knife or other handy implement to be inserted beyond the end of the arm after the plug has been withdrawn from its socket to pull thearm free.

In the form ofconstruction exemplified in Figs. 4-6- there is provideda lamp socket com prising members lila and Ila assembled with or providing parts 12a, I la, la, Ilia, Ila, 25a, Zia, 22a, 23a, 24a, 25a, 28a, 29a, 36a, 31a 38a, 39a, 49a, and 4 10. which are generally similar, respectively, to those parts of the construction of Figures 1-3 which are similarly numbered without subscripts. Instead of the members 26 and 21 a resilient contact piece 50 for the center terminal of an electric bulbis provided on the end of the lead 24a, and a contact piece 5| for the side terminal of the bulb, is provided on the end of the lead 25a.

The member la is formed with a ledge 52 and the" member I la with a ledge 53, which are adapted to rest on the rim 54 of a casing member 55 with which a casing member 56 is adapted to be releasably connected as by screw threads 51. The casing members 55 and 56 are. preferably formed of insulating plastics, and the casing member 56 is formed with a shoulder 58 adapted t o-extend over the ledges 52 and 53, and is internally threaded to receive a bulb.

Since certain changes may be made in the above article and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted illustrative and not in a limiting sense.

I claim:

1. In an electric socket, the combination with an insulating casing including bulb retention means and electric terminals'for interconnection to the bulb contacts, of a connecting mechanism, comprising, an insulating base removably mounted in said casing and having an aperture and a surface, an insulating cover for said aperture hinged to said base and being movable about the hinge axis between closure and release positions, respectively, a cam on said cover having a continuous curvature convexly eccentrically of the hinge axis and disposed opposite said surface when said cover is in closure positionzto squeeze forclamping therebetween an electric cord, and respectively to release the same when said cover is'in release position, said cam being in said closure position near dead center, whereby outward pulling on said cord will urge said cover further towards closure, extensions on said terminals positioned on said base, and means on said cam disposed, in said closure position of said cover, adjacent said extensions and operable to press thereagainst for electric contact the wires of said cord.

2. In an electric socket, as claimed in claim 1, further characterized in that, said surface of said base being curved similar to the curvature of said cam though opposite with respect thereto and concave, whereby an elongated portion of said cord may be gripped throughout therebetween positively while free from cord damage.

3. In an electric socket, as claimed in claim 1, together with, means intermediate said casing and said mechanism operable to maintain said cover in closure position.

4. In an electric socket, as claimed in claim 3, further characterized in that, said casing being composed of at least two parts, and said locking means comprising an annular shoulder formed on said base and said cover and aligned throu hout when said cover is in closure position, and upper and lower ring surfaces on said parts of said casing surrounding said shoulder to maintain closure and oppositely supporting it removably against axial movement in either direction for releasable suspension of said mechanism within said casing.

5. In an electric connector, for use with an insulated cord having a plurality of wires, in combination, an insulating body having an aperture and having a cord receiving recess at one end extending inwardl forming on the body interior a continuous curved depression spaced opposite to and positioned concavely eccentrically of the hinge an insulating cover hinged to said body and being movable about said axis between a closure position wherein it is disposed across at least a major part of said aperture, and respectively a release position wherein it is positioned at an angle thereto, said cover comprising a cam having a convex curvature substantially parallel with and positioned opposite to said curved depression in said closure position of said cover for oppositely gripping therebetween an elon: gated portion of said cord, said cam surface in said closure position being near dead center, whereby an outwardly exerted pulling force on said cord will urge the cam further into gripping position, and all the points of said cam surface being spaced from said hinge axis for a distance smaller than the shortest distance of any point of said curved depression from said hinge axis, whereby said cam may manually be moved between the closure and release positions, said cam in the release position of said cover being spaced from said curved depression and from said recess sufiiciently to release said cord, a contact terminal for each wire disposed on said body and. protruding to the exterior thereof, means connected to said cover and positioned in said closure position adjacent said terminals to press each wire into contact with a terminal, and means operable for releasably locking said cover in said closure position.

6. In an electric connector, for use with an insulated cord having a plurality of wires, in combination, an insulating body having an aperture andhaving on the body interior a continuous surface, an insulating cover hinged to said body and being movable about the hinge axis between a closure position and respectively a release position at an angle thereto, said cover comprising a cam having a convex curvature eccentrically of the hinge axis and positioned in said closure position opposite said surface for oppositely gripping therebetweena portion of said cord, said cam surface in said closure position being near dead center, whereby an outwardly exerted pulling force on said cord will urge the cam further into cord gripping position, said cam in the release position of said cover being spaced from said surface sufliciently to release said cord, a contact terminal for each wire disposed on said body and protruding to the exterior thereof, and means connected to said cover and positioned in said closure position adjacent said terminals to press each wire into contact with a terminal.

7. In an electric connector, as claimed in claim 6, further characterized in that, said protrusions of said terminals including prongs at one side of the exterior of said body for removable connection to an electric outlet.

8. In an electric connector, as claimed in claim 7, in combination with, locking means including a latch positioned at said side of the body exterior carrying said prongs, and so arranged that said latch will be accessible only when the prongs are removed ofi the electric outlet, whereby said cover will be restrained from movement away from said closure position during use of the con nector.

SVEND LAESSE PEDERSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,383,764 Sargent July 5, 1921 1,454,858 Price May 15, 1923 1,700,538 Grant et a1 Jan. 29, 1929 1,991,045 Becket Feb. 12, 1935 2,277,161 Sickinger Mar. 24, 1942 2,233,177 Brainard May 19, 1942 2,408,045 Cottrell Sept. 24, 1946 

